Asus X450CC

[mgrharry]

A friend tried to install a new KB on his Asus X450CC which was working properly, except for dead keys, and afterwords the laptop is dead- no charging light, no quarter fan spin, no signs of life. He did not install the keyboard IO shield so I suspect the bottom of the KB touched the mobo and shorted some component. There is no obvious physical damage to the board, and no visibly burned components. Will post some board pics

[mgrharry]

Re: Asus X450CC

[ktmmotocross]

Re: Asus X450CC

when its not anything wisibly burned why do u think this photo will help?

dont u think some measurement will be better help?

[caspian]

Re: Asus X450CC

In this model of laptop, the keyboard is tightly connected to the laptop's upper cover so that the keyboard will not touch the mainboard. but If you want to replace the keyboard, you should install a number of rubber cubes on the mainboard to hold the keyboard up.
just look at the mainboard to see which components have high probability of being shorted by keyboard's metal surface.

[mgrharry]

Re: Asus X450CC

I will post measurements shortly.

[mgrharry]

Re: Asus X450CC

here are the readings so far.

[mgrharry]

Re: Asus X450CC

Here are the latest updated readings. This area of the board seems most likely to have been touched by the kb. I've also attached the board view for this mobo. Also noticed a loud whine which appears to be coming from the cap on the bottom of the board, PCE8101, which is underneath the pictured area.

[mgrharry]

Re: Asus X450CC

Thoughts anyone?

[ktmmotocross]

Re: Asus X450CC

start from begining. so thats measuring every big grey coil on board for voltage and resistance to ground

[shandybass]

Re: Asus X450CC

start from begining. so thats measuring every big grey coil on board for voltage and resistance to ground

This is how every amateur wastes so much time trying to find a fault. The laptop is dead so the beginning is where the dc enters the board. Readings from there will soon pinpoint the fault area.
Why waste time taking zero readings from "every big grey coil on board for voltage and resistance to ground" when the board is "dead"
The mind boggles

[SMDFlea]

Re: Asus X450CC

This is how every amateur wastes so much time trying to find a fault. The laptop is dead so the beginning is where the dc enters the board. Readings from there will soon pinpoint the fault area.
Why waste time taking zero readings from "every big grey coil on board for voltage and resistance to ground" when the board is "dead"
The mind boggles

Did you look at the picture at post #7 ,there`s 19V at the mosfet, not as dead as you may think .

[ktmmotocross]

Re: Asus X450CC

Did you look at the picture at post #7 ,there`s 19V at the mosfet, not as dead as you may think .

posted at 2:36 AM so maybe hes sleeping allready

[piernov]

Re: Asus X450CC

Measuring voltage and resistance to ground on every coil is very easy and quick to do, and will give a rough idea of what state the board is in, and help pinpointing where to concentrate on the power sequence.

It absolutely makes sense to do so in a no power situation.

[mgrharry]

Re: Asus X450CC

Measured coils. Only the one closest to the dc jack has any voltage. Others show resistance.

[mgrharry]

Re: Asus X450CC

*bump*

[SMDFlea]

Re: Asus X450CC

Edited.Wrong post.

[BlueMidnight]

Re: Asus X450CC

I assume PU8100 pin 15 = 8.6V is a typo and supposed to be .86V to match the .85V on the capacitor connected to it. This is the 3V linear regulator output. Check the resistance from here to ground. Though there may be another explanation for the low voltage..

There is something going on with the power rail feeding PU8100. You measured 19.28V on one side of PR8101 and 11.9V on the other. It is supposed to be a 1 ohm resistor, and could not possibly be dropping that much voltage without burning up. Double-check the voltage readings and check if its resistance has increased from the 1 ohm it is supposed to be.

And then that same 11.9V somehow measures as 12.4V at PU8100 pin 11 (VIN). Probably just fluctuated between the two readings though. Quite possible if the resistor is bad or something like that.

Incidentally, PU8100 is a UP1589Q, which is hard to get info for. However, it is compatible with the RT8239B and has the same pinout.